Measuring device for oil wells



Jan. 29, 1929-.

C. L. REDFIELD MEASURING DEVICE FOR OIL WELLS Filed May 26, 1925 Patented Jan. 29,

casrna LIBEDFIELD, or exercise, trainers.

msuame nnvxo'n iron 011. watts.

a plication medley 26,

My invention relates to [measuring devices for oil wells,and has for its b ectthe provlsion ofmeans for determinin' the relation-.

. of oil to the Well from the oil bearing sand or rock in whichv the well is. V i

i To understand the requirements tobe met by the present devicefit is to be noted that an 011 well is a hole in the ground about six inches in diameter and some twothousand feet, more or less, in de th. The depth of the oil in the well may be anything, 'but will here be as:

sumed to be less than one hundred feet and" liable at any time to subside to a depth of less than ten feet. In wells located near other wells, and operated iundervacuuni,such

subsidence may occur at any time without warning. y p I I The heaters used for heating such wells are usuallyelectr'ic heaters which may be of any type. The heater shown in the application of George S. Hollister, Serial Number 574,649,

filed July .13, 19-22, or that shown in my application', Serial N umber 587,616, filed September 11', 1922, are convenientones to'which the present invention may be applied. These heaters arecylinders aboutfour and one-half inches in diameter and from ten to twenty feet long, A wire cable is usedto lower such a heater into thewell to a position near the bottom, and an electric current is'turned on. As long as the heater is completely submerged in the oil in the well, the circulation of the oil willconvey, heat away, and the heater will not sufler. But if the oil should suddenly subside so as to uncover any considerable part of the upper end of the heater, then the heater would become injured or destroyed by overheating unless the current was promptly shut off. One object of the present device is to give prompt warning at the surface of theground of any such subsidence at the bottourof the well. i we Oil wells have tubularlcasings from the surface of the ground down to-the oil bearing sand or rock, but in this oil bearing part there is no casing. The result is that vthe walls of the oil bearing part of the well frequently cave in and fillfup several feet of the lower end. This is particularly liable to oc- 1923. f Serial No. 841,564. 3

our during heating. If a heater. should be lowered to within a few feet of the bottom of the well, and the wall should cave in so as to cover several feet of the lower end of the heater, then the buried part would become overheated and injured-or destroyed. Another object of the present device isv to give warning of such partial burying of the heater so that overheating may be'avoided.

In the accompanying drawings Fig. 1 is a side elevation of the apparatus at themouth of the well together with a section of the well with the heater in it, butnear the 'top. In this view the len hofthe heater is much reduced as compare to its diameter.

Fig.2 is a front elevation of the apparatus shown in Fig. 1; a Fig. 3-is an enlarged view of part of the apparatus as it appears in Fig. 1; and, Fig. 4 is a section on line 4-4 of F i 1.

. Located adjacent to the mouth of t o well 10is a frame 11 in which is'a slide 12 support- 75. I

ed on springs 13. Carried in the slide 12 isa loose sheave 14 over which runsthe cable 15 for lowering the heater 16 into the well31-0. From. the sheave'14 the cable passesto anidle sheave 17, and from here it extends to an ordinary hoisting apparatus for raising and lowering the heater in the well. That part i of the cablebetw'een sheaves Maud 17is intended to be parallel with that part which extends down into the well. Beyond the sheave 17 the cable may extend in any direction.

In a part of the frame 11, which serves. as a guide for the slide 12,i's a recess 18 vingwhich is a, gear 19 provided with a spindle 20. having a bearing in framell, and secured to the slide 12 is a rack 21 arranged tov engage gear 19 Adjacent to the gear 19 is a light clock spring 22 having one end secured 'to the frame at pin 23 and having the otherend secured to. the

spindle. Itawill be evident that amovement of the slide inits guide willturn the gear 19', and that the spring 22 will act to'take .up all slack between gear and rack in'one direction. The spring is given an initial tension for that purpose. v I

Secured to the frame 11b screws 24 is a dial 25, thru the hub of whic runs the spindle 20. Adjustably secured to the spindle 20 by a nut 26 is a pointer 27 arranged to sweep over the graduations on the dial 25 when the spindle 20 is rotated by reason of the slide 12 moving up or down in the frame 11. Secured to the flange of the dial by a screw 28 (Figqi) is a piece of insulation 29, and on this is-a metal piece'30 having fingers which lie in the pathof the pointer 27. These parts are so constructed that the pointer 27 may pass over the fingers on piece 30, but will make electrical connection therewith when so pass ing. Connected to, the piece 30 and to the frame 11, which latter is in electrical connec-- tion with the pointer '27 thruthe spindle 20, is an electrical circuit 31 including a'bell 32 and a battery 33. It will be evident that any movement of the slide 12 which will cause the pointer 27 to engage either finger of piece 30 will cause the bell 32 to sound an alarm.

On the upper end of heater 16 is an extension 34, and on the lower end is an extension 35. The parts 34 and 35 are of the same diameter as the heater 16, and are three or four feet long, more or less as may be desired. Their function is to act as displacement bodies in the oil of the well at the ends of the heater 16. The lower extension has an additional function which will be described later.

Electric heaters arepretty heavy. A heater ten feet long weighs about 750 pounds, and one twenty ,feet long weighs about 1,200

ounds. This makesfthe ordinary weight of eaters range from sixty to seventy-five pounds per foot in length. The cable used varies from one and one-half to two pounds per foot, with an average of about 1.7 pounds per lineal foot. The heavier cables are used for the .longer heaters, and for the greater degtlfis of well. r

en the heater is suspended in the well near the surface of the ground, the downward pull on the sheave 14 is the weight of the eater plus a shortlength of cable, and this amount is multiplied by two because the pull is verticallydownward on both sides of sheave 14. For convenience, however, we may consider the downward pull on sheave 14 to he the weight of theheater plus the weight of whatever part of the cable is within the well. In this proceeding, the extensions 34 and 35 will be considered as parts of the heater.

As the heater is lowered into the well, the downward pull onsheave 14, and consequently on sl1de12 and springs 13, is increased b "the increasing weight of cable in the well.

he slide 12 is made an easy fit in the frame 11 so that any variation in downward pull will result in compression or expansion of springs 13, and consequently in a movement of the slide in the frame. Asthe gear 19 is pivoted in the frame and the rack 21 is secured to the slide, any movement of the slide is registered or indicated by a corresponding movement of the ointer 27 over dial 25.

.For the sake 0 using concrete figures for illustrating purposes, it will be assumed that the heater, including its extensions, weighs an average of sixty pounds per foot in length, and that the cable weighs two pounds per foot. It will also be assumed that the heater isiof such diameter, or cross sectional area, that when it is immersed in the oil it will displace six pounds of oil for each lineal foot of such immersion. As a matter of fact, the heater may be of any weight per foot, the important things being the varying weight of cable and weight of displaced oil when the heater is immersed.

As the heater descends in the well, the springs 13. will become more and more compressed and the pointer or hand 27 will move over the graduations on the dial. As illustrated in the drawings, this movement will be in a clockwise direction. The graduationsdo not need to be at any particular scale as their principal object is to indicate movement rather than register weight. The relationship' of the springs to the pointer movement may-be such that the increasing weight of cable as the heater descends will cause the pointer to make several revolutions over the face of the dial. The obj ect of such arrangement would be to have small variations of weight make a clearly perceptible movement of the pointer. 7

As the heater descends in the empty part of the well the pointer moves forward, but

the instant the lower end of extension 35 is an additional pull of two pounds on the a cable at thesheave 14, but as soon as the heator enters the oil there is a buoyancy of six pounds per foot of immersion, and that the difference reducesthe pull on sheave 14 by four pounds for'each foot whichthe heater enters the oil. If the total length of heater and extensions is thirty feet, then the total immersion of the l1eater will result in a reduction of one hundred and twenty pounds on the cable, or twice that on the springs-13. The parts may be adjusted so that this difference will make a considerable movement of the pointer'ovei' the dial.

As soon as the heater is fully immersed,- further descent will add to the pull onthe sheave byan amount which will be represented by the difference in the specific gravities of cable and oil. This will change the ward one. When the heater strikes the bot tom of the well, its entire weight is removed from the pull on sheave 14, and the pointer suddenl moves backward again.

It wi l be evident that by watching the pointer and dial, a person can ,tell when the lowered heater. reaches the surface of the oil, when it becomes fully immersed, and when it strikesthe bottom. If the lower- 1,7oo,sse

ing mechanism is provided with means for" determining. at any time what length of cable has been paid out, then these observa 'tions of the movements of the pointer will serve as means for measuring the depth of the oil in the well. 1 Or the depth may be determined by measuring the amount of cable paid'out between the first and second backward movements of the-pointer .whenthe heater is passing from a pointabove the oil to contact with the bottom of the well. Or-

dinarily, a rough estimate of the depth of the oil will be all that is necessary.

In. practice, the heater is lowered to contact with the bottom of the Well'and then is raised two or three feet, more or less, so that the entire weight is clear of any solid sup port. The nut 26 is then released andthe pointer adjusted to a position between the fingers on contact piece 30, as shown in Fig. 3. By again tightening nut26, the pointer is securedjin this "position; The current is then turned on the heater, and permitted to stand that way until .it is considered that the well has been sulficiently heated.

As long as the heater remains submerged,

and nothing special occurs, there will be no" movementof the pointer. But if the oil in the well should subside and'expose the end 34 of the heater, then there will bean increased pullion the cable of six pounds for each foot of heater exposed, and such increased pull will cause the pointer to move,

forward. It the parts are so adjusted to each other that the pointer will move far enough to engage a finger of contact piece 30 beforethe entire lengthv of the extension mally cover'only apart of the extension 35.

A I from ordinary caving of the walls.

Astherc are no heating coils in this exten-' sion, no damage will occur as the result of such caving of the walls. The 'part 35 is normally-a spacing piece to avoid damage Under the heating process, the caving in of the walls below the casin is a process occurring at intervals. The circulation of the oil being heated, and the melting of the paraflin in the pores of the sand or rock, will cause a small caving in which will fill the space under'the heater, and perhaps bury a small portion of 'the extension 35. As the heat increases there is likely to be another cave in which will cover more of extension 35, and after several such cavings the falling material may cover part ofthe heater proper.

If something is not done to overcome this difliculty, such,covering'will cause overheating and damage or destruction of the heater.

But during such process, the cable is also lengthening by reason of'being heated. That part of the cable which is submerged is of the sumetemperature as the oil, which stretching gradually under its load, and it is temperature is continually increasing as the heating process goes forward. Above the surface of the oil, the cable becomes grad-' ually warmer and warmer by reason of the heat in the oil radiatingtto the air in the well over the oil, and also by the upward movement of the vaporized portions of the more volatile parts of the oil inthe well. The com,- bined stretch and expansion of the cable under pull and 'increasin' heat cause the heater to move continually ownward in the well. But if there has been a cave in'of the walls so as to cover even apart of the extension 35, then thedownward movement of the -heater will cause it to rest on the material which has fallen down under it, Thiswill reduce the pull on the cable which inturn will cause a backward movementof the pointer and a conse uent-signal by the bell 32.

rom the foregoing it will be seen that if a heater used in heating an oil well be-subjected to conditions which will cause destructive overheating at either end of the heater, notice of such condition will be given to the operator at or near the mouth of the well. Also, the indicator will give the operator in-' formation as to which end of the heater is in danger. If the upper end is exposed by rea son of subsidence of the oil in'the, well, then the added pull on-the sheave 14 will cause the bell to be sounded by a forward movement of the pointer. If the lower end be endangered I by reason of caving'in of the walls of the well, then the decreased pull on. sheave 14 will cause the bell to be sounded 'by a backward movement of the pointer. And further, the

signal will give the operatorinformationof either kind of accidentbefore that accident has progressed far enough to endanger the heater, or to cause as much damage as would amount to the burning out of a fuse. Caving in of the walls of the well is the most common accident endangering the heater. With this a paratus, the difliculty is overcorne by simp y raising the heater a few feet so that it will be clear of the material which has fallen in.

What I claim is: I 1. The combination with a device sus ended by a cable in the oil of an oil we and used to heat the same, of an indicating device for indicating the occurrence of anaccident liable to result in injury to the heating device, and means for using the expanding length ofthe cable to operate the indicating device so as to 'give information'o'f the occurrence of the accident.

2. The combination with a device for heat J30,

ing the oil in-an oil well,'a.nd a cable by which 3, The combination with a body to be inthe heater is supported within the well, of sel'ted in the oil of an-oil well, and a cable by means operating by decreased. tension on which said body is lowered into the well, of lo .the/eable to indicate a caving-in of the walls means operating thru changed tension on 5 of the well which would bury the lower'end said cable for indicating thedegree of subof theheatet by the material falling from mergence of said body in the oil'of the well.

the walls. CASPER L. REDFIELD. 

